What are the historical markers of Sunni / Shia conflict? Have there been violent conflicts for centuries?

Question

I am interested in anything that explains the complexity of the Iraqi situation.

Answer 1

Tradition says that Muḥammad himself foresaw 72 heretical sects of Islam developing. But today some authorities speak of several hundred.

The two major divisions are the Shia and the Sunni. Each has, however, numerous subdivisions. Of every 100 Muslims, about 83 are Sunni and about 15 Shiite. The others belong to various sectarian groups as diverse as the Druze, the Black Muslims, and the Abangans of Indonesia, who mix Islam with Buddhism, Hinduism, and local religions.

brother killing brother

Answer 2

Good question.